Convert to use poetry & pyproject.toml for dep & build management (#54)

* Convert to use poetry and pyproject.toml, update README

* add some resources for contributors

* minor adjustments

* ci: separate tests from linting, run using poetry

* add pytest-mock to dev requirements

* combine running tests and reporting to codecov

* generate both xml and html coverage reports

* add codecov to dev dependencies

kasa/__init__.py

@@ -11,6 +11,7 @@ For device type specific actions `SmartBulb`, `SmartPlug`, or `SmartStrip`
 Module-specific errors are raised as `SmartDeviceException` and are expected
 to be handled by the user of the library.
 """
+from importlib_metadata import version  # type: ignore
 from kasa.discover import Discover
 from kasa.protocol import TPLinkSmartHomeProtocol
 from kasa.smartbulb import SmartBulb
@@ -19,6 +20,9 @@ from kasa.smartdimmer import SmartDimmer
 from kasa.smartplug import SmartPlug
 from kasa.smartstrip import SmartStrip
 
+__version__ = version("python-kasa")
+
+
 __all__ = [
     "Discover",
     "TPLinkSmartHomeProtocol",